Table 3.
The Proportion of Influenza A (H3N2) and Influenza B Cases That Were Serologically Confirmed as Influenza for Each Intervention, Stratified by Real-Time Polymerase Chain Reaction (rtPCR) Cycle Threshold (Ct) Category (ndicating specimen viral load)
| Group, characteristic | No. (%) of subjects with serologic confirmation of influenza A (H3N2) or B infection No. (%) |
||
| Influenza A (H3N2) | LAIV arm | TIV arm | Placebo arm |
| No. of subjects | 77a | 39a | 41a |
| rtPCR Ct category | |||
| <25 | 15 (88.2) | 4 (30.8) | 17 (94.4) |
| 25–30 | 21 (84.0) | 4 (40.0) | 13 (92.9) |
| >30 to <40 | 31 (88.6) | 1 (6.3) | 7 (77.8) |
| Total | 67 (87.0) | 9 (23.1)b | 37 (90.2) |
| Influenza B | |||
| No. of subjects | 9 | 8a | 7a |
| rtPCR Ct category | |||
| <25 | 1 (100.0) | 2 (100.0) | 1 (50.0) |
| 25–30 | 2 (100.0) | 1 (33.3) | 0 (.0) |
| >30 to <40 | 6 (100.0) | 2 (66.7) | 2 (100.0) |
| Total | 9 (100.0)c | 5 (62.5) | 3 (42.9) |
NOTE. LAIV, live attenuated vaccine; TIV, trivalent inactivated vaccine.
a
Appropriate blood specimens necessary to determine infection immune response were not available for all subjects.
b
For TIV vs placebo arms, P < .001 (by χ2 test).
c
For LAIV vs placebo arms, P < .05 (by χ2 test).